After the inspection, 25V, 3.6V voltage for display were normal. After in the light is dark observation display folk. It is found that the characters are very dark fluorescent display, although very disordered but it is believed to display no problem. Careful observation, found that every time when the open / shut down, the head can not be back, that the servo, driving circuit is not working. The reasons for the analysis of the servo circuit are: 1. The working voltage of the servo circuit is not normal. 2, servo circuit chip or peripheral circuit fault. 3, the system control circuit on the servo system without control data output. Check the power supply voltage of the servo circuit, are normal, but the servo chip SSL9287 8, 9 pin voltage is not normal, respectively, 4.7V, 0.3V. SSL9287 8, 9 feet is the clock signal, external 16.9344MHz oscillator and two patch resonant capacitor. The feet of the normal voltage is about 2.3V, if not normal that the clock oscillation circuit of servo circuit not, servo circuit and thus can not work. When the boot after the replacement of crystal oscillator in 16.9344MHz, screen display and a / warehousing key function returned to normal, corresponding to the screen display character also display correct. But the CD does not turn, screen will display "no disc". If the machine is switched off, the screen will disappear, the key will fail and the failure will be a recurrence. Try to exchange the original crystal and then immediately start, in addition to the disc does not rotate, screen, / warehousing function returned to normal. Analysis of crystal distance closer to weld leg and two chip capacitors, welding oscillator, high temperature soldering iron to damage the capacitor may temporarily returned to normal, so doubt there is a problem with the two chip capacitors, and the original crystal should be no problem. Try a 100PF ceramic capacitors replaced voltage 0.3V at one end of the chip capacitors, and then boot, results all the faults were disappeared, the machine back to normal work. Because I do not know the value of the original chip capacitor, and the 100PF capacitor can work, it is no longer try to find the capacity of the original capacitor.

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